


Dipper's Big Change

by HeWhoIsMany



Category: Gravity Falls
Genre: Age Progression, Gender or Sex Swap, Transformation
Language: English
Status: Completed
Published: 2020-11-21
Updated: 2020-11-21
Packaged: 2021-03-10 02:01:05
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,568
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27655853
Author URL: https://archiveofourown.org/users/HeWhoIsMany/pseuds/HeWhoIsMany
Summary: Dipper is excited when his Grunkle Stanford takes him to show an old experiment. But a strange malfunction turns Dipper's life upside down.
Comments: 1
Kudos: 9





	Dipper's Big Change

Summer vacation for Dipper had been, to sum it all up in one word, weird. He’d met first-hand and fought various beings most people considered fictional, such as gnomes, zombies, and ghosts. He’d met the girl of his dreams only to realize that there wasn’t really any hope of them getting together one day. He’d recently learned his Great Uncle Stan had a twin brother, also named Stan, who had been trapped outside their universe until Grunkle Stan freed him.

Oh, and Stanford? He’s the six-fingered man who wrote the journals that had been Dipper’s guidebook to all things supernatural.

One particular early morning, Dipper was following his Grunkle Stanford out into the forest surrounding Gravity Falls to help him with an experiment. “Now, you have to understand is that the dimensional boundaries that separate this world from all the others is thin in Gravity Falls, Dipper,” the scientific genius explained. “But there are patches here and there where they’re even thinner, so thin that I was able to try out some interesting ideas of mine.”

Dipper was soaking all of this into his brain, eager to learn more. He cursed himself for forgetting to bring a notebook and pencil for proper notetaking. “So, what kind of device are we looking for?” Dipper asked, excited. “Is it another portal? Or maybe a time machine?” Dipper had already traveled through time a few times, but that had been from the future, seeing it being built in the present would be something else entirely.

Stanford laughed at that, waving a six-fingered hand idly in a random direction as he replied, “No, but not bad ideas. Still, the portal we have is too dangerous as it is, and time travel is overrated if you ask me.” Through his thick glasses lenses, it looked as though Dipper’s grunkle had spotted what he’d been looking for, and he picked up pace as they walked towards what looked like a natural cave in the side of a large rocky outcropping. “Here we are! You’ll be able to see for yourself!”

They entered the cave together, Stanford quickly turning on a flashlight when the light levels started to get lower and lower as they descended deeper into the earth. Finally, after a sharp turn, they reached what they’d been looking for. Rocky walls covered in wet condensation sharply transitioned into a divided plastic barrier, and behind it, the workspace of a scientist. Stanford ushered Dipper through the decontamination room, and then cleared off an incredibly dusty worktable once they were inside to show off what they’d come there to see.

“Haven’t you ever wondered if there were other versions of yourself living in other dimensions, living lives just like yours, except when they weren’t?!” Stanford asked, to which Dipper immediately nodded. How could a weirdness buff like him not wonder about things like that, especially once he’d learned that interdimensional travel was not only possible, but a living reality. “Well then, I call this the Dimension Mirror. All you need to do is look into the reflection and use the buttons to toggle between dimensional frequencies! You can look at all the different possibilities of your life!”

It was almost too much for Dipper to believe. The device looked just like a thicker than normal mirror, with several settings at the bottom, including the directional arrows Stanford had pointed out. There was also a button clearly labeled for power, which Dipper reached out to get the thing going. But while there was a definite change to the mirror’s reflection, instead of showing some other world, all it showed now was static. That made Stanford frown. “Seems like the dimensional barometer in there might be out of dimensional mercury. I’ll have to go grab some from the home lab.” He must have seen that Dipper was a bit disappointed to hear they’d have to wait, because he clapped a hand on his great nephew’s shoulder and told him, “Dipper, you guard the room while I’m gone, okay?” Before Dipper knew it, Stanford was gone and he was alone with the Dimension Mirror.

Feeling as though he’d been entrusted with an important task, Dipper resolved to do his best and make Stanford proud, keeping his hands to himself and waiting patiently for him to return.

His resolve broke in under five minutes. To be fair, he thought as he started changing the dimensional setting on the mirror, he lasted a lot longer than Mabel would have. Strange glyphs appeared in one corner of the mirror every time he hit the button, like they were the channel number on a television, but each one Dipper checked was just more static. Starting to feel impatient, he started hitting the button rapidly, cycling between dimensions as quickly as possible.

For a flash of a second, something besides meaningless fuzz filled the mirror, and Dipper quickly used the other button to go back until he found it again. Now the mirror was reflecting the room he was in, the same down to every detail. The only thing different in the reflection was who was standing in front of the mirror.

The person on the other end of the reflection looked a little like Dipper. They had the same shade of brown in their hair, the same pasty skin tone, and if Dipper was right from a brief glance at something the person’s bangs were hiding, the same constellation birthmark on the forehead that gave him his nickname.

But that was basically all he and this figure had in common. For one thing, they weren’t a guy. Their face, while a little similar to Dipper’s, had a kind of femininity inherent to it that just couldn’t be denied. The large breasts silhouetted under the reflection’s long-sleeved red blouse were another dead give-away. This person also looked a lot older than Dipper. At the very least, she was as old as Wendy, but Dipper had the feeling she was even older than that, probably closer to Soos.

She looked just as confused as Dipper felt, and they reacted to what they saw in almost the same way, reeling back before looking closer and seeing if their movement was really mirrored. It wasn’t exactly, there were small differences to timing, but in a broad sense they were doing the same kinds of things.

What neither noticed was that the Dimension Mirror was starting to arc with electricity. It hadn’t been used in ages, and even with the sealing equipment Stanford has used, it was starting to encounter too many errors to handle. Which was why, when Dipper reached out to touch the surface of the mirror, something unexpected happened. He and the figure in the mirror both received shocks of electricity, making Dipper cry out in pain as he pulled his hand back. The reflection was gone, replaced by static once more.

Dipper started to panic. His incredibly cool uncle had given him an important responsibility, to safeguard a key instrument he’d invented years ago, and instead of just doing that Dipper had broken it. He was going to be so mad, Dipper thought. Or even worse...disappointed. He was just about to scream in frustration when he doubled over in sudden pain...something was wrong with his body!

The first thing to change was his height. Dipper was kind of short even for someone at his age, but that quickly changed as his body stretched out, only stopping when he was almost six feet tall. There was a popping sound that filled the air one by one as his joints had to accommodate his growing bones, giving him far longer arms and legs. The room looked so much smaller to him now, thanks to the change in perspective. But that growth had another effect, namely that his clothes no longer fit him in the slightest. His jeans were digging into his hips, and it was hard to breathe at all with how tight his shirt and jacket were.

But the changes didn’t stop there. The next thing to happen was something focused more in his lower region. Before this day, Dipper’s hips were, to be frank, basically nonexistent. Even aged up into an adult, Dipper had the skinny build of someone who could cut glass with their knees. Now, muscle and fat packed into his thin legs and flat butt in what many would call the perfect proportion. His legs suddenly had an appealing curve to them, and his butt was large and shapely enough to maintain lift while still being damn impressive to look at as it walked away. With a sharp  _ crack _ , his hips widened out to match his prestigious posterior, putting enough room on each side for someone to rest their hands there comfortably.

This was all too much for Dipper’s poor jeans to handle. Already stretched farther than the fabric was ever meant to withstand, tears started to form before Dipper could even really understand what was happening to him. It started with one rip, down the center of his butt, but that wasn’t enough to alleviate the strain, and soon what had once been a pair of blue jeans was now just scrap sitting at Dipper’s feet. The underwear he had on under them wasn’t doing that much better, clinging tightly to a very different set of genitals. There was no bulge at all in those boxers, and when they finally shred to pieces too, his new feminine parts would be revealed to the open air for the first time.

When it came to Dipper’s torso, the changes were a lot more light. His waist cinched in a little tighter, helping with his growing hourglass figure. But there was far more work to be done with Dipper’s chest. Tissue started to build up, swelling the area around his nipples, which were suddenly larger and very alert. The growing breasts spelled the doom for Tipper’s shirt, which tore apart even as Dipper’s bust showed no signs of stopping anytime soon. They grew bigger than Wendy’s, into something one would expect to see in a pornographic magazine: large and full, perky and firm, and entirely natural. Well, as natural as breasts given to someone by a piece of unimaginably advanced technology can be, anyway. And now they were on Dipper’s chest, jiggling in the open air, only partially covered by his vest.

The last changes to take effect were a little less bombastic. Dipper’s face shifted as a sharp sound of bones crunching and moving in strange ways filled the air, leaving it finished as an exact copy of the woman he’d seen in the mirror. Looking down at himself, Dipper realized, he looked exactly like her from head to toe now. He was a fully adult woman, an incredibly attractive one at that, and nearly naked.

Some part of Dipper, who was largely still trying to understand what the hell had happened to him, latched onto the thought that he looked more than a little strange only wearing a vest, men’s underwear, and some hiking boots. So, without anything else to do really, Dipper stripped out of those, leaving him completely naked. If it hadn’t been for the heating installed with the rest of the little lab Standford had built, Dipper might have gotten hypothermia from doing that.

He was still trying to piece together exactly what he was going to do when he heard someone approaching. Before Dipper could even think to cover himself, his great uncle rounded the bend, holding a satchel full of what he’d thought he needed to repair the issue he’d seen. “Well, Dipper, are you ready for science?” he was asking, smiling, when he noticed who was standing there. They were spared any sort of identity miscommunication, luckily, thanks to the pine tree hat still on Dipper’s head and the vast experience of strange things Stanford had built up over his life. Sighing, the older man asked, “Alright, what happened?”

After going through decontamination to come into the room again, Stanford listened attentively as Dipper explained every detail: the channel-surfing, the dimension he’d found, and the zap that triggered the changes. When it was done, Dipper, who still hadn’t gotten used to his feminine voice or feminine body, asked, “Is there any way to change me back?”

Stroking his scruffy chin, Grunkle Stanford considered the issue. “I’m guessing that if we managed to find that same dimension you had on the mirror earlier, the woman you saw would now look exactly like you did. The device must have built up a series of faults, as well as a serious power overload. When you both touched it at the same time, it thought you were dimensional faults and ‘corrected’ you both by changing your bodies to what the other had.” None of that really made much sense to Dipper, though perhaps it would have sunken in better if his brain wasn’t still struggling to deal with the bombardment of new sensations his changed body was giving him.

Starting to feel annoyed with his grunkle, Dipper put one hand on his wide hips and asked, “Okay, but what about fixing it?” The science of it all was a lot less interesting, Dipper cared a lot more about just getting it over with.

Grunkle Stanford looked confused by the question. “Hmm, well I’m not even sure how to theoretically manage that. But don’t worry too much about that, I can give you my coat, and you can ask your friend Wendy for some help getting used to things while I work on the problem.” Dipper was slack-jawed hearing that, and only barely registered Stanford telling him, “It shouldn’t take too long, two weeks at the most. No, make that a month.”

That was how Dipper suddenly found himself with the body of an adult woman, but that wasn’t the only thing to have changed. As he struggled to get used to what was to be his new normal until his Grunkle fixed things, Dipper realized his mind had changed too. It was becoming more and more used to his new body, for one thing, but there was more than just that. He found himself bonding with Wendy and even Mabel more, and suddenly Soos seemed a lot harder to be around. Grunkle Stanley was even worse. Half the time, he looked like he wanted to catcall at Dipper, the other half he just looked mortified at what had happened to his great nephew.

Oddly enough, the strange highlight of this all was Robbie. It seemed the teenager was instantly enchanted by Dipper’s feminine charms, even knowing that it was the same person he’d bullied before. Dipper wasn’t going to do anything with it, he realized that Robbie was way too young for him, but it was fun to be appreciated a little, so he led the boy along a little.

A week into this new life, just as Dipper was starting to actually like it, Grunkle Stanford came back from another day at the cave looking different himself. Now he looked like a beautiful, matronly woman, a similar change clearly having afflicted Dipper. Looking completely unphased by it, all she told Dipper as she walked through the house was, “Doing some control experiments with that universe’s me, but it’s looking a bit tricky.” Dipper laughed. It would be fun to have another woman in the house.


End file.
